5 ton electric hoist hook blocks is very important for the safe work of lifting machinery, so there are very strict requirements for the material and processing of the hook.
Because the high-strength steel is actually very sensitive to cracks and defects, the materials used to make the hooks are some special high-quality low-carbon static steel or low carbon alloy steel. The grades of steel are DG20,DG20Mn steel and DG34CrMo.
After forging and stamping, after annealing after mechanical processing of the hook group, actually high strength, good plastic toughness and other characteristics.
Disc hooks are commonly used in large tonnage places exposed to intense heat.
The disc hooks are usually made of A3, 20 or 16Mn steel plates with a thickness of not less than 20ram, and do not break suddenly and are highly reliable.
As the fracture caused by defects is limited to a few steel plates, the remaining steel plates can still support the lifting weight, only a few steel plates can be replaced, the hook plate sheet cannot be broken at the same time, so it has greater safety.
However, the plate hook can only be made into rectangular section, so the strength of the material can not be fully utilized.
Because casting material has a lot of quality defects, such as shrinkage hole, shrinkage, thermal stress, slag, etc. Defects, easy to produce cracks, not easy to be found, so the use of cast steel hook for lifting machinery;
The welding hook cannot be used, because the welding has defects such as gas hole, slag inclusion, lack of penetration and cracks.
Nor can hooks be made of steel with high strength and low impact toughness.
For forging the hook set, it shall be marked with rated lifting weight, inspection mark, inspection mark, inspection mark, date, number, etc., on low-stress printing, and shall be provided with qualified documents after surface inspection and load test by the forging plant.